Enameled tank



C. E. MURPHY ENAMELED TANK Sept. 28, 1943.

2 Sheets-Sheet 1 Filed Nov. 25 1940 INVENTOR. C//WE/f /J f wf ATTORNEY.

Sept 28, 1943 c. E. MURPHY ENAMELED TANK Filed Nov. 25, 1940 2Sheets-Sheet 2 INV Alk.

f4 VMH www m ,w m f. a Q w Patented Sept.. 28, 1943 STATES PATEN orticaENAMELED TANK Application November 25, 1940, Serial No. 367,075

1 Claim.

` becomes perforated by the corrosion and a leak results destroyingfurther usefulness of the tank for its intended purposes. For a numberof years it has been the practice to galvanize the tanks walls to resistsuch corrosion, lbut because the tank is a closed container, at the timethat the coating is applied, it is next to impossible to produce acontinuous solid galvanized coat on the inner wall by any known'galvanizing method; and a single uncoated spot will corrode and becomeperforated in as short a time as if there were no coating at all.

The useful life of the usual galvanized hot Water tank therefor islittle if any longer than that of an ungalvanized one.

Metals and allo-ys having corrosion-resisting properties have beenproposed for the Walls of such tanks to prolong their life but suchtanks are too expensive for the general market.

The cheapest and most practicable known fabricating process for makingthe tank Walls, is to make the Walls in pieces from sheet steel and tojoin them together; and to render such a steel tank corrosion proof, ithas been proposed to coat the tank walls, particularly the inside Wall,with vitreous enamel, that is to say enamel formed by ring and fusingdried enamel slip. The tank walls may be variously constructed but theapplying of the enamel coat presents difoulties. The enamel coat must beabsolutely complete and solid so as not to expose even a single uncoatedspot of the steel wall ho-wet er small to the corrosive action of thehot water; and for this reason, if welding' be used in joining the steelparts of the Wall, the welds must be contrived in some manner so thatthe enamel as applied will not contact the Weld itself, because if itdoes it will not form-solidly thereover, with the one exception ofelectric flash welding the flash of which has been tooled ofi down tosolid metal.

Again, if parts of the wall are joined by rivet,- ing. spot welding,roll welding, etc., so that one part overlaps another with intermediatecrevices, foreign matter which unavoidably nds its Way into saidcrevices, or which is produced therein by (Cl. 22o-55) the weldingoperation, will vitiate the enamel coat during the formation thereof sothat it will not formsolidly or completely thereover. And if the jointsbetween wal1pieces are not perfectly rigid, one part will have movementrelative to another when the tank is subjected to internal pressure, andeven if suchrelative movement is so slight as to be imperceptibleWithout delicate measuring instruments, it still is suicient to crackthe glasslike brittle enamel coat thereat and admit the corrosive hotwater to the steel of the wall.

The general market and manufacturing facilities and economies demand ahot Water tank of the form comprising an elongated cylindrical body and-heads at each end of the body. If the body wall of such a tank, whichlfor the sake of economy -must be made of as thin metal as practicable,comprises any portions which are gen,- erally planar, or out of round,they tend to become mo-re truly cylindrical under the internal pressureand this deformation Vwill crack the enamel; or if there are any curvedwall portions of any shape which under pressure become straightened outby the longitudinal pressure on the heads which tends to stretch thebody, their deformation also Wlll crack the enamel. Cracking of theenamel at any point on the inner wall of the tank will start corrosionthereof.

It follows therefore that a successful enameled hot water tank cannot bearrived at by taking just any known steel-walled tank and attempting tocoat it with enamel.

After many experimental attempts to make such a tank I have found thatthe above indicated problems can be solved and herein I have describedthe preferred construction and method of making such a tank.

The preferred construction comprises a cylindrical tubular Ibody ofrelatively thin steel with a ash-Welded lc-ngituidinalv seam tooled offdown to solid metal and the' body trued up to cylindrical form; a heavyring of steel surrounding the outside of the body andwelded to it neareach end. and the ends of the body anged and coined over the rings; apair of dishe'd peripherally flanged heads of outwardly curved orgenerally ellipsoidal sectional form at eachy end of the body and ofsuiiciently thick sheet steel to resist deformation by internal tankpressure; and means to sealedly attach the heads to the ends of the bodythrough the agency of the rlngs.-

With'the body parts thus made separately, they can each be enameledyseparately and the enamel coat thoroughly inspected for imperfectionsbefore the parts are assembled in the completed tank; and the formationof a perfect enamel coat is facilitated during the enameling process;

and all liability of enamel cracking during assembly or by internalpressure after assembly is avoided. n

Ihe present invention relates particularly to means by which theenameled heads of such a tank are attached to the enameled body.

It is among the objects of this invention therefore:

To provide generally an improved construction of enamel-coated tank forcontaining fluid such as hot water under pressure;

To provide improved means for attaching an enameled tank head to anenameled tank body;

To provide improved means for attaching an enameled tank head to anenameled tank body which allows for variation in the dimensions of thehead and body which occur during the manufacture thereof;

To provide an improved construction of clamping device or means forclamping the enameled peripheral ange of a tank head upon the enameledperipheral flange of a tank body with sealing gasket materialtherebetween to effect an improved internal pressure-proof andleak-proof juncture between the head and the body;

To provide in connection with a head clamping construction such asreferred to above, improved cover means to cover and conceal the same.

Other objects will be apparent to those skilled in the art to which myinvention appertains.

My invention is fully disclosed in the following description taken inconnection with the accompanying drawings in which,

Fig. 1 is a side elevational view partly broken away of a tank embodyingmy invention in one form;

Fig. 2 is a top plan view of the embodiment of Fig. 1;

Fig. 3 is a fragmentary longitudinal sectional View to enlarged scale ofa part of the tank of Fig. l illustrating in the preferred form a meansof attaching a head to a tank body and a cover element for covering theattaching means;

Figs. 4 and 5 are views similar to Fig. 3 illustrating a modificationand the mode of operation thereof to compensate for dimensionalvariations which may occur in the construction of the parts of the tank;

Fig. 6 is a view similar to Fig. 3 illustrating another modification;

Fig. 7 is a view illustrating a modification of a bolt device which Imay employ, one form of which is shown in Figs. 4 and 5; Y

Fig. 8 is a view taken in the direction of the arrow 8 of Fig. 7;

Fig. 9 is a view similar to Fig. 7 illustrating another modification; f

Fig. 10 is a view taken in the direction of the arrow IIl of Fig. 9;

Fig. 11 is a view similar to Fig. 3 but illustrating anothermodification;

Figs. 12 and 13 are views illustrating the mode of operation of themodification of Fig. 11 to compensate for dimensional variations whichmay occur in the construction of the parts of the tank; Y

Fig. 14 is a view illustrating steps of the process which may beemployed in the formation of a clip device shown in Fig. 11;

Fig. 15 is a view similar to Fig. 3 showing the head-'attaching means ofFig. 3 for the head at the opposite end of tank;

Figs. 16, 17 and 18 are other views similar to Fig. 3 showing othermodications.

Referring to the drawings, Figs. 1 and 2. wherein I have illustrated oneform of a tank embodywhich are the conduits 4--4 connected to the head2.

The body I is preferably constructed by rolling a sheet of steel intothe form of a hollow cylinder and ash welding the abutting edges thereoftogether at a longitudinal joint indicated at 5 in Fig. 3. A heavy steelring 6 is tack Welded or spot welded to the outer wall of the body Iinwardly of the end of the body and then the end of the body is bentand, coined over the ring 8 to form a ange l.

'I'he ring 6 has preferably a corner 8 which is coined into the metal ofthe wall where the flange 1 joins the cylindrical body I, and thecylindrical body I is then trued up to remove any planar or out of roundportions. Rings 6 and flanges 1 are provided on each of the oppositeends of the body I, and by the fabricating process employed, when theopposite end heads 2 and 3 have been attached to the body wall throughthe agency of the rings 6, and internal pressure exerts longitudinaltension in the Wall I, there is no part of the wall which is out ofround or which tends to straighten out in the axial direction, anddeformation is prevented, for the purposes referred to.

After the flash has been trimmed off from the weld 5 down to solid metaland any other roughness on the wall of the body I flange 'I or ring 6has been removed, the body flange and ring are coated with a coat ofvitreous enamel 9.

The heads 2 and 3 may be alike except in some cases as to a diierentnumber of conduits 4 connected thereto. I'he head 2 as shown in Figs. 1and 3 is generally of hemi-ellipsoidal crosssectional form having aperipheral flange I0 lying substantially in a plane transversely of thehead and continuing peripherally into a depending skirt II. The flangeI0 has a circular series of bolt perforations I2 therein the seriesbeing substantially concentric with the axis of the head.

The head including the ange I0 and skirt II are coated inside and outwith a coat of vitreous enamel I3, the perforations I2 being providedeither before or after the enameling process.

By making the body separate from the two heads and enameling the threeparts separately, the formationA of an unbroken solid coat of enamel isfacilitated inasmuch as oxygen-containing air is free to flow over allthe surfaces being enamel-coated. This free ilow of air facilitatesdrying the wet enamel slip uniformly and without sweating and during thefiring of the dried slip the essential presence of oxygen on all partsof the surfaces of the pieces is readily attained. Forming the piecesseparately permits a thorough inspection of the enamel coat thereon foraccidental imperfections.

To assemble the head with the body, a sealing gasket I4 is laid on theange 1, and the head flange I0 superimposed thereon and the head flangeis clamped upon the body flange with the gasket therebetween by thefollowing means.

Bolts I5 are projected downwardly through the perforations I2 and theirlower ends are threaded into washers or plates I5 overlapping andbridging the under side of the enameled ring 6 and the lower terminationof the skirt 1. The bolts I5 are then turned by their heads I1 and bythe clamping action exerted between the heads and the plates I6, thehead flange I is drawn down tight upon the body flange I to effect apressureproof and liquid-tight seal at the gasket I4.

'I'he skirt II performs a number of functions. Since the bolts I areradially outward beyond the gasket I4, the latter acts as a fulcrum overwhich the flange I0 tends to bend and it might bend and crack the enamelon the flange if it were not for the skirt II, but the presence of theskirt prevents such bending because in order for the flange IIJ to bendthe skirt II would have to be compressed or deformed, and the skirt IIbeing disposed at right angles to the plane of the flange Ill it acts asa beam of relatively great depth and gives rigidity to the flange I0 andprevents it from bending. This is important because bending of theflange I0 would crack the enamel.

Again, since the gasket I4 is compressible, and since the boltsl I5 mustbe spaced one from the other in their circular series, the force of thebolt heads I'I would tend to force the flange I0 into the gasket I4 atpoints opposite the bolts and allow it to remain bulged upwardly atpoints between the bolts and this would tend to crack the enamel, butthe skirt II contributes such rigidity to the flange I0 that this actionand enamel cracking is prevented. Again, theskirt II at its lowerperipheral edge provides a base upon which the plate or washer I6engages for the clamping purposes described above. Again, the skirt IIcovers the bodies of the bolts I5 and conceals them, rendering neat inappearance what would otherwise be a complicated appearing boltedstructure.

The under sides of the heads I'I of the clamping bolts, may be generallyspherical as indicated in Fig. 3 so that they will engage theperforations I2 on the end edges thereof and thereby prevent mutilationof the enamel as the bolts are turned.

The diameter of the skirt II is made dimensionally such that a space I8may preferably be left between the bolts and the enamel coat on the ring6 and so that a space I9 may be left between the bolts and the skirt II, and the perforations I2 are located on a circle of such diameter thatthe bolts will extend downwardly between the skirt and the ring so thatthese spaces I8 and I9 will be substantially equal. v

A number of advantages accrued from the employment of the constructiondescribed above which are not apparent without further consider,- ation.In the making of the head 2 by the usual press-forming operation,strains are set up in the metal. When the enamel coat is applied themetal is heated to at least a cherry-red color so that the heads tend towarp. The flange I0 may warp slightly out of a true plane, or if it isall in one plane it may warp slightly out of parallelism with planes atright angles to the axis of the body or of the head itself, and theskirt II may warp slightly out of cylindrical form. Similarly the ring 6and body I may Warp slightly out of round and slightly out of planarform at the ring and ange '1. Again, the perforations I2 may not lieexactly on a circle or upon a center line circle of exactly pre-selecteddiameter, and

if accurate die means is used to punch such perforations they may notlie in their pre-selected positions after the head is enameled because,of the above-mentioned warping which may take place.

By means of the above-described.construction which includes the spacesI8 and I9, considerable tolerance in the dimensions and shapes referredto is permitted and therefore although, out of a number of heads andbodies, no two heads and no two bodies may be exactly alike, any twoheads may be mounted as described upon any of the bodies, and thuscomplete interchangeability is provided not withstanding that theallowable tolerances are very great, both as to accuracy in making theparts in the first instance and as to warpage due to subsequent heating.

While the warpage referred to is` not of sufcient degree to cause theWall or head to deform under pressure in use and crack the enamel coat,it may be enough to interfere with assembly of the parts, if suchtolerances are not provided.

If desired, the joint structureabove-described in connection with Fig. 3for the upper head may be made still more neat in appearance by thefollowing means. A sheet metal cover 20 is pressformed or spun fromsheet metal, which may be light in gage, and comprising a planar cupbottom 2| and a cup skirt 22. A large perforation 23 is made in the cupbottom. After the head has been attached to the body or after the tankhas been installed, or brought to the' place of installation, theperforation 23 is telescoped over the upwardly curving part of the headas shown with the skirt 22 depending around and covering allof the partsof the joint and the cup bottom .2l may rest upon the heads Il of thebolts to support the cup-form element as a joint cover. The cup-formelement 20 may be externally plated or plated and polished if desired orit may be enamel-coated and of the same or of a dillerent color from theexternal enamel 9 and I3 giving a very neat and ornamental appearance tothe entire structure, and since the head 2 is enameled separately fromthe body I, it may have a different color from that of the body.

In Fig. 15 this same joint structure of Fig, 3 is illustrated for thelower head 3 and a cup form cover device 24 may be provided having askirt 25 with the bottom of the cup resting upon the ends of the boltsl5 as shown in Fig. l5. The cover device may be put on before the headis attached.

In Fig. 6 is illustrated a modification of the clamping means. Hereinstead of the bolt I5 and plate or washer I6 of Fig. 3, a J-bolt 26 isused, the short leg 21 of the J engaging the under vside of the enameledring 6, the long leg of the J extending upwardly through the perforationin the flange I0 and having threaded thereon aconstruction is the sameas that of Fig. 3 except that the bolt in this case 29 is projecteddownwardly through the flange I 6 with the head 30 of the bolt restingon the flange, and with a nut 3| on the lower end of the bolt below theplate or washer I6, and the nut having if desired a rounded or sphericalunder side as shown at 32 in engagement with the plate I6. The plate I6is in this case provided with a perforation through which the boltextends loosely and as the nut 3| is drawn up tight, the plate willassume the right angle position with respect to the bolt indicated inFig. 3 or will rock one way or the other into bridging and clampingengagement with the skirt II and ring 6 as shown in Fig. 4 or Fig. 5depending upon whether in the inal assembly the combined thickness ofthe ring 6 and flange 1 and the packing washer I4 brings the lower sideof the ring 6 below or above the peripheral edge of the skirt II.

Instead of the bolt and nut arrangement of Figs. 4 and 5 the bolt andnutarrangement of Figs. '7 and 8 or that of Figs. 9 and 10 may beemployed the construction and mode of operation of which it is believedwill be apparent without further description from the above-detaileddescription of Figs. 4 and 5.

In Fig. 11 is illustrated a further modification which in addition tothe above-described tolerance advantages has a centering action and aninter-locking action. As shown in Fig. l1 the ring, in this case 6A hasthe under side 33 thereof formed generally conical sloping inwardlyupwardly, the ring on the opposite end of the body sloping inwardlydownwardly as will be understood. The clamping plate 34 has a main bodyportion 35 engaging the lower edge of the skirt Il and for averagetolerances being horizontally disposed and has an-angularly oset endportion 36 engageable with the under side 33 of the ring 6A. A nut 31rounded on its under side and engaging the plate 34 is threaded on thebolt 38. When the nut is drawn tight, the plate 34 bridges the skirt IIand ring 6A as described above and the offset portion 36 of the plateinterlocks with the ring. When all of the plates and bolts have beendrawn up circumferentially of the structure this interlock preventslateral shifting of the head with respect to the body and centers thehead with respect to the body. If an accumulation of the above-mentionedtolerances causes the plate body 35 to take up an inclined position, theplate may assume the position of Fig. 12 or that of Fig. 13 as describedabove.

The plate 34 may be made from a sheet or strip of metal 39 as shown inFig. 14 by rst perforating it as shown at 40-40 and then shearing ittransversely as at 4I- 4I and then bending portions 36-36 out of theplane of the strip, the plate in such event being generally U-shapedwhereby it may be assembled with the bolts 38 by lateral movement afterthe nut 31 has been run loosely on the bolts. The bolts 38 may thus beput in the head loosely before the head is brought to the position to beassembled with the body which shortens the assembly time for assemblingthe bolts with the head.

Obviously a U form plate with or without the offset portion 36 may beused with others of the forms described and to be described. Theinclination from the horizontal of the plates in Figs. 4, 5, 12 and 13is exaggerated in the drawings to more clearly illustrate the principle.

In the foregoing I have illustrated and described my invention in itspreferred embodiments, and inFigs. 16, 17 and 18 I have shown furthermodification embodiments which I may employ in the practice ot myinvention when desired.

As indicated by the construction in Fig. 16, the body I may lat thegasket-engaging end thereof be variously formed. It may terminatewithout the above-described flange 1 as shown at 42, or the end may berolled or folded over as indicated in broken line at 43. In theabove-describedpreferred forni, the under side of the ring 6 provides ashoulder against which the bridging washer or plate I6 engages and asindicated in Fig. 16, this shoulder may be provided otherwise forexample by pieces such as 44, corresponding in number to the plate I6and welded to the outer wall of the body I inwardly of its end.

In the modification of Flg. 17 the ring 6 and flange 1 are provided asbefore, the under side of the ring 6 providing the said shoulder, buthere the bridging element 45 is in the form of a ring surrounding thebody I and the central opening 46 of which is large enough so that whenthe ring is shifted to one side it may be telescoped over the ring 6 andthen centered around the body I whereby it will engage. the under sideof the ring 6 as a shoulder, and the bolts 41 are threaded into the bodyof the ring to effect the clamping action.

In the modication of Fig. 18, a ring 6B is provided over which theflange 1 is bent and into the corner 48 of which it is coined asreferred to above. The ring I6 may be welded to the flange 1 asindicated at 49. The ring 6B which surrounds the body I may be ofsuflicient radial extent as shown to engage both the under side of theange and the peripheral termination of the skirt in this case IIA, theilange 1 itself constituting the shoulder means and the ring 6Bconstituting the bridging means by which the clamping action of thebolts 50 is erfected.

A consideration of the forms of Figs. 16, 17 and 18 in connection withthe preceding forms more completely described. show that with respect tothe clamping of the head upon the body vo en'ect a seal at the gasketthe structure comprises any Iorm for the end of the lbody which engagesthe gasket a specific formf/ being a ange such as the nange l; andsnolder means or some kind on the body which may be tne under side ofthe ring 6 or the under side of the ,nange l, the latter as in Fig. 18,or separate abutments such as 44 in Fig. 16; bridging means between theskirt of the head and the shoulder means which may be separate washersor plates I6 or which may be a ring as in Figs. 17 and 18. And thevarious modifications illustrated and described indicate that otherforms of body and shoulder means and bridging means may be provided 'byother modications and by changes and combinations of the iorms shown sothat my invention is not limited to the exact details of constructionillustrated and described but is inclusive of all such modications andchanges which come within the scope of the appended claim.

I claim:

In a tank construction a tubular tank body, a ring surrounding the bodyadjacent its end and welded thereto, a flange on the end of the bodyextending outwardly radially over the ring, a head having an annularsubstantially planar portion opposite theflange, a compressiblyyieldable gasket between the annular head portion and the flange, askirt on the head surrounding the flange and ring and radially spacedtherefrom, a circular series of bridging elements bridging the ring andthe skirt, and a circular series of threaded bolts disposed in the spacebetween the ring and the skirt and projected through periorations in theplanar portion and the bridging elements and provided with heads andnuts to exert a clamping action on the bridging elements and planarportion to clamp the gasket between the head and the flange, a coat ofvitreous enamel on the planar portion, and the skirt being sumcientlyrigid to prevent bending of the planar portion and crack- 5 ing ot theenamel coat by the clamping action at the bolt perforations therein.

CHAIMER E. MURPHY.

